Chapter 2: Overview of the Western Communications Intelligence System during World War II

During the Second World War, the United States and Great Britain operated the principal Western Allied code-breaking agencies. The Commonwealth countries of Canada, Australia, and New Zealand, and Britain's colony of India provided substantial support with personnel and material, especially in the Middle East, Pacific and Asia theaters of combat. There were lesser contributions from small European national detachments that had escaped from Poland, France, and the Netherlands East Indies. By war's end, this multinational effort had brought to a high-level of proficiency a worldwide system that intercepted, decrypted, translated, and disseminated intelligence derived from Axis and neutral communications.1

A popular perception about Western communications intelligence and its subsidiary code- breaking function, often generally referred to as "Ultra," was that this information was available from all Axis and neutral sources at all times to the Allied commanders and leaders. This view is simply not true. The war between the Axis cryptographers to devise and emplace systems to protect their communications and the Allied cryptologists to collect and exploit those same communications (and the mirrored struggle between Allied cryptographers and Axis cryptologists) was marked by victories and defeats on both sides. Although there were major successes by the Allies early in the war, notably the exploitation of some versions of the German Enigma and the Japanese diplomatic machine system, known as Purple, the struggle for cryptologic supremacy was not settled until the midpoint of the war when the full resources of the Allied cryptologic effort finally achieved a general and consistent inroad into most, but still not all, major Axis cryptographic systems. Even then, there remained gaps and shortcomings in the overall Allied capability that produced unpleasant tactical military surprises for the Allies later in the war, such as at the German Second Ardennes Offensive in December 1944. Several Axis and neutral cryptographic systems were never exploited due to a paucity of Allied intercept, the strength of the particular Axis code or cipher, or the late date of a cryptographic system's introduction into operation. In short, the Ultra success by the Allies was never total or constant when measured in terms of the total number of enemy or neutral codes and ciphers that could be broken or the duration of their exploitation. Where the Allies succeeded was in the exploitation of those Axis communications and cryptographic systems that were critical to the conduct of certain battles and campaigns. This ability also allowed the Allies the ability to gauge the strategic intentions of Berlin and Tokyo in a depth that otherwise would have been lacking if there had been no recourse to the information from Ultra, Magic, and the host of other systems.2

Trying to describe or graphically represent the entire Western COMINT system can be difficult. Some initial attempts were made by the U.S. services. One of the more popular early graphic efforts was a chart devised by the War Department's G-2 (Intelligence), "A Message from Originator to MIS." This version was taken from the postwar Army history The Achievements of the Signal Security Agency in World War II and is reproduced here.3 It illustrated the system that started with the transmission of a message by an originating entity. It then detailed several intermediate analytic steps to the point where the translation of the original intercept was disseminated to the War Department.

The system this chart illustrated was limited to those cryptologic functions from intercept to translation that were performed by the Army's Signal Intelligence Service at Arlington Hall. The chart failed, though, to describe why a certain message was to be intercepted in the first place. There were numerous Axis and neutral radio terminals and networks to intercept. What was the process that determined which one was monitored? Similarly, the chart also left out what happened to the intelligence after it reached the Pentagon. To whom did this information go and how did it get there? Was it handled any differently than intelligence from other sources such as captured documents? In short, the chart failed to explain the place and role of cryptology within the context of the activities of the larger Allied intelligence system.

The production of Allied communications intelligence during World War II was a multistep system. It began with the determination of a hierarchical priority of intercept of Axis communications and was completed with the dissemination of the intelligence derived from it. This system can be likened to a "closed cycle" in which all steps were interrelated. Within this process a significant change to one step affected all the others. For example, a reordering of requirements due to a change in capability or a crisis in a military theater's situation would affect what was collected and processed. The rise or decline of cryptanalytic effectiveness, efficiency, or advances in technology or techniques could affect what terminals would be monitored in the future and what intelligence gained from them would be disseminated and to whom it would be sent.4

Besides being distinguished by the interdependent nature of its operations, the COMINT system, especially as practiced by the British, was noteworthy for the operational interaction of its analysts That is, individuals at all points in the system contributed information that others could use in their separate jobs. This interaction deve-loped partly from the background of a large number of the individuals who worked in the cryptologic agencies during the war. Many people who worked at Bletchley Park and Arlington Hall were current students, graduates, or faculty recruited from universities and other schools that prized cooperation and an intellectual detachment. And a majority of these hires were women.5 More so, the leadership of the cryptologic agencies encouraged the continuation of this free flow of ideas and information. Even those who merely logged in intercepted messages were encouraged to contribute insights and observations.6 One high-ranking American observer, who visited Bletchley Park in May 1943, noted that the British personnel approach was " bold and forward-looking… an imaginable conception of the possibilities of obtaining results from attention to details and infinite pains."7 The result of this approach was a system, which was described by William F. Friedman as "unified at the top and operationally intimate below."8

The wartime Western Allied communications intelligence system consisted of the following steps: setting requirements, priorities, and division of effort; intercepting messages; processing the intercept; and disseminating the resulting intelligence. Each step consisted of a number of subordinate processes that contributed to its completion, though each process was not employed against every intercept or cryptographic system. Also, each step was affected by a number of technical and institutional constraints, as well as political/strategic influences or contingencies that further determined how effectively a step was carried out. Many of the subordinate processes and the constraints and outside influences for each step will be described in the proceeding sections.

Two other aspects of the Allied COMINT system need to be considered before we proceed with the description. First of all, when we talk of an Allied system, we are really describing two distinct national systems, that of the United States and Great Britain. While both countries carried out similar communications intelligence activities, we shall see that there were a number of differences between them in organization, security restrictions, equipment, training, and even technical jargon. Like much of the rest of the special relationship between the United States and Great Britain, the wartime Anglo-American COMINT relationship was marked by a search for ways to make the two national systems work in a more cooperative fashion.

Another characteristic of the wartime allied cryptologic agencies was the phenomenal growth experienced by both as the war progressed. In 1939 cryptologic organizations that barely numbered a few hundred were, by war's end, staffed by tens of thousands of civilians and military personnel. As a representative register of this massive growth, consider that the U.S. Army's signals intelligence arm was producing about forty translations a week in January 1942. By the time Japan surrendered, it was turning out about 1,025 translations a week.9 Also, during the war, both the GC&CS and the SIS grew organically. They had to design, build, refine, and modify their organizations, equipment, structure, practices, and procedures while they also worked against Axis cryptography and communications. In 1939 American and British COMINT were local cottage workshops. By 1945 they had become a joint global industrial concern.

What follows is a description of the communications intelligence system with a particular eye to the ways in which its operations influenced how it obtained and distributed intelligence about the Holocaust.

Step 1: Setting the Requirements, Priorities, and the Division of Effort

For the Allies, perhaps the most difficult step in the COMINT process was simply to decide what Axis communications to intercept, decipher, and report. To visualize the potential size of the Axis communications target is to grasp the scope and nature of the problem facing the Allied cryptologic agencies, especially early in the war: thousands of radio terminals on hundreds of radio networks around the world supporting Axis military, naval, diplomatic, security, intelligence, and commercial entities. All of these utilized hundreds of cryptographic systems from simple hand ciphers to complex book codes and intricate machines such as Enigma, Purple, and Tunny.10 Added to this initially uncharted wilderness were the hundreds of military, diplomatic, and commercial communications networks of important neutral and Axis-friendly countries, notably Vichy France, Turkey, Sweden, Spain, Portugal, Switzerland, the Vatican, and those of Latin America. These networks, too, had potential as sources of intelligence and could not be ignored; many already were targets of Allied cryptologists.

Early in the war, the Allied communications intelligence effort could not adequately monitor the existing Axis communications networks, much less even hope to cover it completely. The British, beginning in September 1939, and later the Americans in late 1941, lacked the facilities, the personnel, and the technology to adequately monitor all of the Axis terminals that mattered. It would take time for the influx of money, training, and the development of administrative and technical support organizations to create the impressive Allied COMINT structure that existed by the end of the war.

Meanwhile, the disparity in capabilities between the Allied cryptologic agencies and the Axis communications networks forced the intelligence staffs in Washington and London to prioritize the Axis communications terminals and cryptographic systems that had to be attacked. This prioritization was determined by a number of general factors. First of all, there had to be either an already demonstrated or a reasonably high expectation that intelligence of value to the war effort could be derived from a terminal's messages. Another factor, which could override all others at times, was the perceived current strategic or tactical military needs of the moment. For all practical purposes, these factors were military-oriented. They dictated target listings throughout the war and dominated all prioritization schemes from strategic priorities to those in individual theaters of operation.

The COMINT agencies, too, had their own considerations to add to the calculations for target priority. Usually, these considerations reflected the agency's own measure of its technical ability to intercept or to exploit cryptanalytically a particular Axis terminal or a general target category such as "Japanese military." The feeling within the SIS leadership, for example, was that tasking of radio links was far more complex than to be left to the whims of intelligence officers. In early 1943, the SIS disagreed with the idea that the War Department's G-2 could just hand it a list of radio terminals to go after. One memorandum stated that there were other factors "in the chain of events leading from G-2's desires to actual results." Rather, it continued, the priority of a target radio terminal should be determined first by whether a monitoring station could hear it and then whether any cryptographic systems used in its traffic could be read or were being studied.11

As an example of how requirements were levied and how they changed with the war, it is useful to look at the experience of the SIS. For the overall U.S. COMINT effort, the SIS was responsible for intercepting and processing Axis military, weather, and air force communications traffic. It also was responsible for exploiting international diplomatic communications. This was a carryover from its success with the Japanese diplomatic cipher machine known as Purple. In April 1942, G-2 gave the Signal Security Service (SSS), as the Signal Intelligence Service was soon to be called, a set of priorities for collection and processing (which included cryptanalysis and translation).12 The first priority included all German, Japanese, and Italian military traffic. Second priority was given to all Axis military attaché communications. Axis diplomatic traffic among their respective capital cities was in the third priority. The fourth priority was for all so-called German "administrative" radio nets, which probably referred to German illicit intelligence and security radio networks. The diplomatic messages of other countries, minor Axis and neutrals, were spread across priorities five to eight.13

Nearly a year later, in March 1943, the priority list had changed somewhat. The priority list for collection and analysis was organized now into groups identified by letters that ranged from "A," the highest, to "G," the lowest. For the SSS, the Japanese Army was now the most important target. This was tagged "#1 Special Research Project," which probably referred to the main Japanese army code that was still unexploited at the time.14 Weather traffic was also part of Group A, as were certain diplomatic links between Tokyo and Moscow, Berlin, and Rome. German military had fallen to the bottom of Group "B," along with Japanese diplomatic messages to Europe (other than other Axis capitals) and "Security" (intelligence, espionage and security elements such as police) messages.15 The latter reference to "Security" traffic is interesting because the SSA still lacked the means to intercept consistently the communications of the German security agencies such as the Abwehr (military intelligence), the SD, and the German Police. The Americans had few monitoring sites that could intercept such communications in the European theater. There were some U.S. Army radio intercept companies in England and North Africa, but they were tasked with collecting tactical German military radio traffic. A note attached to the tasking for these intercept units indicated that the coverage of the German security elements was primarily for the purpose of tracking the volume of traffic and reporting this to Army counterintelligence.16

The SIS already was somewhat familiar with German Police communications and cipher systems. In January 1941, then SIS Major Abraham Sinkov, one of William F. Friedman's original cryptanalytic staff, had headed a small technical exchange mission to GC&CS. It was this mission that provided the British with a working Purple and Red Japanese diplomatic cipher machines. During the ensuing technical discussions, one of Britain's foremost codebreakers, John Tiltman, provided Sinkov with detailed information on how the so-called German Police cipher worked. He was informed that the descriptor "German Police" applied to the systems used by the Schutzpolizei, the SD, the SS, and the line Order Police battalions and regiments. Sinkov was told that the information in the police messages was useful for mapping associated German military units.17 However, at the time the U.S. had no way of intercepting these communications; the cryptanalytic information was useless except for training.

As for the remainder of the revamped 1943 SIS overall requirements, these consisted mostly of targeted diplomatic communications from most minor Axis, neutral, and some minor allied nations. As in the previous year's priorities they remained spread across the lower priority Groups from "C" to "G." For example, the tasking requirement for intercept of diplomatic messages between Washington and major neutrals was now at the Group "D" level. The requirements to intercept diplomatic messages from the Vatican, Latin America, and European countries to elsewhere other than Washington were covered in Groups "E" and "F."18

In the various combat theaters of operation, cryptologic working arrangements between the British and Americans followed de facto national theater command responsibilities. In Europe the British were preeminent for the first two years of the war. A gradual cooperative effort with the United States Navy's OP-20-G cryptologists developed during the lengthy U-boat campaign in the Atlantic. In the European Theater of Operations (ETO), the GC&CS, and the supporting British service units, remained the principal Allied cryptologic agency when it came to the Axis military and air force. In the Pacific theater, the American army and naval cryptologic organizations supervised allied intercept and code-breaking operations. In the China-Burma-India Theater, there were British stations in Ceylon and India that had American contingents. Also, Canadian, Australian, and New Zealand personnel served at various Pacific and Asian sites with the Americans and British.

These worldwide operations required that the United States and Great Britain eventually had to establish corresponding divisions of effort and responsibility for setting requirements, intercept, processing, and dissemination. Otherwise, there would be problems with redundant operations, and misallocated resources. Also, the rules, methods, material, and channels for technical and intelligence exchanges needed to be ironed out between the two countries. The two countries had to make a general agreement to govern operations around the world. For the first eighteen months of the war, the GC&CS and the SIS and OP-20-G had a number of separate and limited reciprocal interchanges. By mid-1943, these various working relationships were institutionalized in a series of agreements between the British and the U.S. War Department, which culminated in the so-called BRUSA (Britain-United States of America) Agreement of June 1943.19 (The U.S. Navy would sign a separate, more limited, agreement. It was known as the Extension Agreement and applied to an earlier 1942 exchange arrangement known as the Holden Agreement.)

The main provisions of the BRUSA Agreement were the exchange of technical intelligence (sources and methods) and a division of effort in the daily activities of collection, analysis, and dissemination of intelligence. The two Allies formally agreed to the exchange of finished intelligence. There was no exchange of "raw" (undecrypted) intercepts, except for U-boat messages, and possibly some examples for training purposes.20 The monitoring sites, though, would send their "raw" intercept to the national center responsible for processing it. The agreement did not include so-called "nonservice" (nonmilitary) intercepts. This uncovered category principally entailed Axis and neutral diplomatic and intelligence-related (illicit espionage and internal security organization) messages. Both countries continued individually to decrypt and exchange diplomatic translations, though a later mechanism for exchange between GC&CS and Arlington Hall was established in August 1943. As a result of this later agreement, the two Allied cryptologic agencies targeted the diplomatic traffic of every major Axis power, minor Axis ally, minor Allied power, and significant neutral, though the total amount collected against each country varied. As for the category of Axis intelligence messages, another division of effort was arranged. The British collected and processed German intelligence and security-related messages in occupied Europe: the United States, principally the United States Coast Guard, collected and processed Axis overseas illicit and overt espionage radio traffic, notably Abwehr messages from Latin America, North Africa, and the Far East.

In essence, the BRUSA Agreement formalized the realities of the division of effort in the combat theaters that had existed since 1942. The Americans took the responsibility for Japanese service and nonservice communications, while the British oversaw that of the German and Italian military and security forces. This agreement did not preclude either country from collection and analysis of each other's missions. In fact, both sides exchanged personnel who were then integrated fully into each other's efforts. Three special SSA units were established in Britain to work alongside the British in the areas of collection, analysis, and security. American cryptologists could be found at various British intercept and analytic sites, including Bletchley Park. U.S. radio intercept units stationed in England and North Africa intercepted and analyzed Axis communications in the European and North African theaters, but they passed the take to the British analytic centers.21

Great Britain retained authority over the production of communications intelligence in Europe, while the Americans controlled similar activity in the Pacific. Because of this division of effort, German military communications remained a lower priority for the U.S. Army codebreakers at Arlington Hall Station for the rest of the war.22 Tactical communications intelligence, that is, intercept and analysis of plaintext messages or those encrypted by low-level codes and ciphers that were sent by Axis tactical or operational-level combat units, was produced by Allied cryptologic elements attached to Allied military commands or units in Europe and North Africa. Theater or local commanders controlled the operations of these units and were the main recipient of that type of communications intelligence.

As mentioned above, the priorities for collection and processing shifted during the war according to current strategic needs and capabilities. This shift was especially obvious when it came to diplomatic targets. A good example of the shifting priorities of an individual target country's communications can be seen in the Allied effort against Switzerland's diplomatic radio traffic. During previous European conflicts, Switzerland had remained neutral. As a result, that nation had taken on certain roles such as representing the foreign interests of belligerents. These included monitoring the conditions in prisoner-of-war and internee camps, supporting International Red Cross relief activities, and allowing Swiss locales to be used for unofficial contacts between combatants. Considering these historic roles, Switzerland's diplomatic communications naturally were a target of interest for the Allied cryptologic agencies.

The GC&CS had been analyzing Swiss diplomatic messages since 1939, and the Americans began their separate attack in December 1942. But both agencies produced few translations during this period. There were some technical reasons for this paucity of communications intelligence. One was that for their European message traffic the Swiss relied mostly on the European cable network that was inaccessible to Allied communications monitoring sites. In addition, the Swiss used a large number of codes and ciphers — over ten systems, mostly manual ciphers and codes, and an early version of the Enigma cipher device for their diplomatic traffic. Yet, the most important reason for the small output of translations of Swiss traffic was that, early in the war, the messages to and from Bern appeared to carry little intelligence of value.23 The intercept of Swiss diplomatic messages continued for the purposes of training and cryptanalytic continuity, but not for reporting intelligence. By early 1943, the Americans downgraded the intercept priority of various Swiss diplomatic terminals to fourth and fifth priority on its list.24

This situation changed in the summer of 1944 when the Allies discovered that the Swiss diplomatic cables now carried important information on the conditions in the Balkan capitals that were being overrun or threatened by the advancing Red Army. Of particular interest was the situation in Budapest, Hungary. The several changes in governments and the German-supported coup in October 1944 had kept the Hungarians in the conflict. Furthermore, the Germans were in the midst of a roundup, which had begun in the summer, of the sizable Jewish population in Hungary for transport to the death camps and slave labor details in German war industries. A review of the diplomatic translations from this period issued by the SIS shows a marked increase in the number of published translations of Swiss diplomatic messages. Allied interest in the Swiss diplomatic messages continued late into the war as concern grew over the possible fate of prisoners and internees under Japanese control. The Swiss, working in concert with the International Red Cross, reported their findings on camp and prisoner conditions throughout Asia. Another point of interest for the Allies concerned the activities of German banking officials who were negotiating payments and commercial accounts with the Swiss for German purchases of war material and currency exchanges. (See pages 104-110 for more details on this last point.)

One of the problems that bedeviled Allied cryptologists who tried to set requirements was that the intelligence value of the information carried on various communications networks or individual terminals could not always be predicted. The above example of Switzerland shows how reality did not always match expectations. On the other hand, useful intelligence could come from unexpected sources. For example, one of the best sources for insight into Nazi Germany's strategic plans and Hitler's own appreciation of possible Allied moves came from the Purple decrypts of Japan's ambassador in Berlin, Baron Oshima Hiroshi. Oshima had developed a rapport with most of the Nazi hierarchy, especially Hitler and Joachim von Ribbentrop, the German foreign minister. They confided to Oshima some of the Reich's most important secrets. These personal connections made his long reports to Tokyo a gold mine of information on a number of topics, from German development of new weapons to Hitler's own appreciation of the Allied troop strength and strategic options for landing in Western Europe in 1944.25 Oshima reported nothing on the concentration camps or massacres in the western Soviet Union, though a few of messages to Tokyo suggest he was aware of the situation of the Jews. (See pages 100-101)

In a similar fashion, British codebreakers were probably surprised by the first bits of information about the massacres and camps that appeared on certain German Police radio networks, such as those servicing the police units in the Soviet Union and SS and SD units in occupied Europe. The Allied intercept and processing of German Police and SS communications originally was performed as a supplementary source to intelligence about the German military, principally to gather administrative data and order of battle information. The police and SS communications also contained intelligence on German civilian morale and other domestic security concerns, information about the results of Allied air raids, and escapes by Allied POWs.26 The police messages were also targeted since the manual cryptographic system used was similar to systems used by Wehrmacht units.27

However, London and Washington would never make gathering intelligence about the fate of Europe's Jews and other groups targeted for destruction by the Nazis a major requirement for agencies like GC&CS and SIS. Both would collect and process some information about the roundups, massacres, and the camps from Police and diplomatic communications. Yet, this information was a byproduct, perhaps even incidental to the coverage security and diplomatic nets. The primary purpose of the COMINT requirements placed on Bletchley Park and Arlington Hall was to gain intelligence dictated by the military exigencies of the war. Whatever advantage was gained from the intercept of Axis communications related to the Nazi atrocities was of little use to the current Allied prosecution of the war, except in a limited way for propaganda against the Axis.28 Later, the British would gather it with the intent to use intelligence as evidence in proposed postwar war crimes tribunals. (See pages 50-51 for eventual fate of this intelligence.)

Step 2: Intercepting the Messages

After the requirements had been set, the next step was intercepting the radio terminals that were designated the highest priority targets. It was at this juncture in the communications intelligence system that the general requirements had to be translated from the vague entries such as "German military" to a list of targeted radio stations that could be monitored by Allied radio intercept personnel. Before discussing the allotment of target stations to monitoring stations, it is necessary to describe the communications the Allies monitored. There were two major types of communications media that were targeted: cable (or wire) and radio. Both had their advantages and shortcomings.

The first of these, cable intercept, proved to be a useful but limited source of communications intelligence. At the war's outset, both the United States and Great Britain invoked wartime information contingencies and imposed restrictions on telegram and cable traffic to, through, and from both countries. All such wire traffic — personal, commercial, and diplomatic — was subjected to censorship review. Each resident foreign diplomatic mission was required to submit a copy of each message it sent, even in its encrypted form, to the appropriate government censorship office. The main reason for this was to control the flow of information out of the country that was critical to the war effort.29 In England, the General Post Office oversaw this program, sometimes referred to as "traffic blanketing."30 The British also implemented censorship practices at all overseas Commonwealth cable terminals located in such places as Malta, New Delhi, Gibraltar, and Barbados.31 In the United States, the government, through the Office of Censorship run by Byron Price and staffed by civilians and contingents from the Army and Navy, received copies of all such wire traffic (before transmission overseas or upon receipt from an overseas terminal) from the various cable and wireless telegram companies such as Mackay Radio, Western Union, Radio Corporation of America, and Global Wireless.32 These companies had terminals in New York, Washington, DC, New Orleans, Louisiana, Galveston, Texas, and San Francisco, California. Copies of cable traffic that passed through overseas U.S. and British terminals on to other countries were also collected under the wartime restrictions. This coverage affected mostly diplomatic, personal, and commercial cable traffic between Europe, the United States, Latin America, and Africa.

This cable intercept had the primary advantage of simplifying the intercept problem. All messages flowing through an American or Commonwealth terminal were accessible to Allied cryptologists. Another advantage was the errorless copy of the intercepted cable message; each message usually was free of transmission garbles and missed cipher groups that could hinder exploitation, except for errors by the originator's code clerk. The collection of cable messages was inexpensive for the cryptologic agencies since the national censorship offices performed the task.

On the other hand, there were limitations to this collection method. For example, only cables sent between Washington (and other U.S. terminals with overseas connections such as San Francisco, New Orleans, and New York) and an overseas terminal were available to the Americans. Messages sent on cables not routed through American- or Commonwealth-controlled terminal stations were beyond intercept. There were few means then to obtain these cables except through covert means, such as placing taps or suborning cable clerks. These methods risked eventual exposure and were difficult to hide and continue without discovery by foreign security agencies.

Another difficulty was that some of the targeted countries knew or suspected that the Allies probably were reading their cable traffic. To defeat the intercept and possible exploitation of their cables, some diplomats were warned by their capitals to take certain precautions when sending cables, even encrypted ones. For example, Axis diplomats in Europe and the United States were told to be careful when they included excerpts of public speeches and newspaper stories in their messages. They were warned not to quote them verbatim because the excerpts were also available to Allied codebreakers and could be used as "cribs" to break the enciphered messages. 33 To defeat the Allied cable censors, some countries sent sensitive correspondence by diplomatic pouch or courier. Of course, the courier pouches could be searched covertly ("tossed" was the expression) by Allied agents. But this technique was difficult to arrange and, if discovered, was a possible source of diplomatic embarrassment. It appears that Allied agents probably did this anyway. In early 1942, the U.S. Office of Strategic Services, and its predecessor, the Office of the Coordinator of Information, received copies of diplomatic messages from the British Security Coordination. A number of these messages appear to have been obtained in this manner.34 (See pages 65-6).

In occupied Europe, Nazi military and occupation authorities made use of cable telephone or telegram systems where available, thus denying the Allies access to these communications. Also, during the years of the war, the Germans, especially the military, expanded, repaired, and improved the European cable backbone network in occupied Europe in order to support their operations. In four years, the German army nearly doubled the size of the European cable trunk network to 6,900 miles.35 This cable expansion denied more intercept to the Allies.

The other and much larger and lucrative source of Allied intercept was radio communications. Since its introduction at the turn of the century, radio communications had expanded dramatically. As technology advanced and industry was able to mass-produce components and radio sets, the speed and distances that information could be transmitted grew. Many advanced countries had developed complete national-level communications networks that served private and public functions. When the war began, governments quickly took over many facilities and converted them to military or other official uses. The use of these in place systems presented more problems for Allied intercept stations since they had to match Axis capabilities.

Many Axis and neutral diplomatic missions, not needing or trusting the Allied-controlled cable systems, transmitted their diplomatic messages by long-range, high frequency (HF) radio.36 Axis naval and air force units and organizations relied on long-range HF radio for their communications, unless ground-based cable systems were available. Some communications operated on lower frequency bands similar to those used by commercial broadcast stations. Many Axis units used low-power high frequency radios to communicate with their local commands that reduced the chance for interception by Allied monitoring stations.

The Axis used different modes of communications on the many frequency bands. The most common mode was manual morse, the famous "dit-dah" or on-off keying of a continuous wave signal. This mode appeared on all frequencies, and all service and government elements used it. The Axis also used teleprinter systems for high- volume traffic among command centers, though this appeared late in the war. Voice communications was also heavily used. Most often this appeared at higher frequency ranges. The most common users were aircraft pilots communicating among themselves and with ground controllers. Some aircraft and ground stations used long-range HF voice systems, though this was rare because of the lack of security.37

German Police units operating in the western USSR used both long-range high frequency and the shorter-distance low frequency and medium frequency manual morse communications to send reports about their activities from major command centers in Minsk and Kiev to headquarters back in Berlin. Police battalions received radio or courier reports from companies and detachments in the field. The battalions, in turn, sent their radio reports over HF radio to regimental headquarters in the region in which they operated.38

For the Allies, intercepting Axis and neutral radio communications of interest presented a myriad of problems. The most obvious problem, as mentioned earlier, was simply the number and location of Axis radio terminals — perhaps several thousand. In order just to hear these radio stations meant that the Allies had to develop extensive corps of thousands of radio intercept operators to man the monitoring stations to collect the Axis and neutral communications for intelligence.

The major Allied radio intercept organizations were, for the British, the Radio Security Service (belonging to M.I.6), the General Post Office, and those units of the various services of the British armed forces, known as the "Y-Service." For the Americans, the radio intercept personnel were assigned to the Signal Intelligence Service (Army) and organized under the Second Service Battalion, OP-20-G (Navy), the United States Coast Guard, the Office of Strategic Services, and the Federal Communication Commission. Canada operated the Examination Unit of the Canadian National Research Council. A number of men and women from other Commonwealth countries also performed as intercept operators. These included personnel from Australia, New Zealand, and India. Commonwealth military personnel who performed intercept services were organized into units known as Special Wireless Groups. Additionally, contingents from smaller Allied forces also intercepted Axis communications.

All of these personnel were stationed at monitoring facilities located around the world. These facilities ranged from large field stations, such as at Beaumanor, Leicestershire, England, or Vint Hill Farms in Virginia, to small direction finding huts in Alaska or Scotland. It is difficult to get a precise total number of Allied monitoring sites. Many stations did exist for the duration of the war. Some served only to support a campaign. Many stations were limited to a direction finding function only. Some sites, such as the U.S. Navy station at Muirkirk, Maryland, originally were commercial radio stations that were taken over by the military. American sites, including those of the Army, Navy, Coast Guard, OSS, and FCC numbered over seventy-five. British and Commonwealth stations numbered around sixty and were located in the British Isles and overseas in Australia, Ceylon (Sri Lanka), Egypt, Palestine, Malta, Iraq, Kenya, and India.

Generally, Allied overseas monitoring stations supported the commands in the theater of operation in which they were located. For example, in early 1942 U.S. Army radio intercept companies that were assigned to locations in the British Commonwealth, such as in Northern Ireland, or in the Atlantic region, at sites in Iceland and Newfoundland, intercepted German military, naval, or espionage communications.39 In the Pacific and Asian theaters, some field stations were manned by a mix of personnel from the United States and Commonwealth countries, such as the large sites at Central Bureau Brisbane and the Wireless Experimental Center in India. Other facilities were manned almost exclusively by personnel from one nation, such as the Americans at the U.S. Navy radio intercept site in Hawaii and the British in Ceylon. On the other hand, in the Southwest Pacific area of operations, Australian detachments accompanied SIS units to forward intercept sites in New Guinea and the Philippines to support General MacArthur's advance.40

Most field sites were controlled and manned by one service element: army, navy, air force, or security service, such as M.I.6 or the OSS. This arrangement was not absolute; other service contingents or nationalities could be present. Also, intercept missions could cross service boundaries and responsibilities. For example, early in the war, U.S. Navy sites did collect diplomatic communications. But service priorities usually prevailed when it came to mission assignment. For example, a tentative 1943 intercept assignment list for the major SIS monitoring station #1, located at Vint Hill Farms, Virginia, was dominated by international diplomatic and commercial terminals. The number one assignment block included all government traffic between Tokyo and Rome, Bern, Vichy, Ankara, and Stockholm. The second and third tier priority was both German and Italian weather traffic (known as "WX"). The fourth priority was all government traffic to and from Berlin to Manchukuo, Madrid, occupied China, and Lisbon. Interestingly, the only military traffic assigned to Vint Hill Farms was that of Germany and it was reserved for the lowest priority.41

Eventually, the assignment of targets by city (or "circuit") and specific types of messages was dropped because it was considered inefficient. Too often, there was needless duplicative copy of the same radio traffic. In mid-1943, the SIS adopted the procedure of tasking by frequency and terminal callsign. This targeting method was similar to that used by the British when tasking their field sites.42 The British also pioneered the central control of all collection sites. From Bletchley Park, GC&CS could direct the activities of all the British intercept sites, though its measure of control over service monitoring stations may have been less certain.43

By early 1944, the American and British sites were experimenting with a joint and centralized authority that controlled collection of important target networks. Field sites informed a control authority by teleprinter of current targets being collected. The control station then assigned any remaining priority target terminals that were not being monitored. Field sites also sent in weekly reports on their coverage that allowed refinement by oversight committees in both countries, the Y-Committee (later Y-Board) in Great Britain, and at Arlington Hall.44

Still, even with the number of intercept and direction finding facilities that eventually would be built during the course of the war — over 130 — the Allies would never have enough monitoring positions and radio receivers to match the number of Axis transmitters and the volume of radio traffic they sent. Precise numbers on messages transmitted by the Axis and those intercepted by the Allies are not readily available. One estimate is that a Japanese area army command could send as many as 1,400 messages a day.45 Some educated estimates by veterans and scholars of Allied wartime cryptology tend to support the contention that Allied intercept never resembled the popular analogy to a vacuum cleaner in which all Axis traffic was "scooped up in the ether." If anything, Allied intercept more closely resembled a form of "sampling." There is one estimate that the U.S. managed to intercept only 60 percent of all Japanese naval communications in the time leading up to and at the time of the Japanese strike at Pearl Harbor.46 In rare cases, where the high-level interest existed that could focus resources, more complete coverage could be arranged. During the United States-Japan negotiations leading up to Pearl Harbor, all but a few of the messages between Tokyo and its embassy in Washington were intercepted. But such thorough coverage was not the norm.

Besides the large difference between the level of Axis communications and the Allied monitoring capability to collect it, there were a number of other technical limitations that hindered complete and effective Allied intercept operations. Atmospherics, such as local weather and the presence of sunspots, affected reception of communications, especially those on the high frequency range, which was the most commonly used transmitting frequency band. The location of monitoring stations was critical to hearing enemy transmissions. The sheer distance between the transmitter and the monitoring station could determine whether the latter could hear its target. The time of day and the season could also influence the range and clarity of communications. At night, the composition of the layers in the atmosphere changes, producing two effects: increasing the range at which radio communications can be heard, while creating nonreception areas, known as "skip zones." The local topographic conditions in which a radio transmitter was located played a role in how well a radio signal could be heard at an intercept site. Mountains, heavily forested terrain, or jungle dampened radio transmissions, while deserts increased the range of a transmission. The frequency and power output of the transmitting terminal also mattered. The sensitivity of the monitoring equipment at an intercept site was a crucial element.

All of the above environmental factors were considered when the Allies selected locations for their monitoring stations around the world. An important part of this process was the work of teams that performed field studies of potential sites. The results of their surveys determined the location of the monitoring stations.47 One of the most productive Allied intercept stations against Japanese military communications originating from Japan was the U.S. Army's site at Two Rock Ranch outside of Pentaluma, California. An U.S. Army site that specialized in intercepting international diplomatic communications was located near Asmara, Ethiopia.

At the monitoring station, the capabilities of individual intercept operators could make a distinct difference in what was copied or missed — the difference between so-called "clean" copy usable by cryptanalysts or linguists, or that riddled with missing or mistakenly heard characters or groups that hindered recovery of message text. The ability of Allied intercept operators varied according to training and experience. The training of these specialized personnel included gene-ral skills in communications procedures and modes of transmission, as well as training tailored towards specific communications targets, such as instruction in the difficult Japanese telegraphic kana code. As intercept operators gained experience, their "copy" would become usable.

Two sites primarily intercepted German Police communications. The first was the British Army Y-station at Beaumanor in Leicestershire, located about eighty miles northwest of London, England. Beaumanor was one of the largest British intercept sites and operated with 140 radio receivers by the end of the war. The primary mission of Beaumanor was German military communications and included that of the German Police. Because of the vast distances between the operational police units and their various headquarters hierarchy that extended back to Berlin, a variety of radio frequencies were used. These extended from the low frequency band associated with commercial broadcasts up to the standard high frequency bands used by the military.

The site was able to copy police messages from Russia on all of these frequencies. In fact, once the initial recovery of the police radio network was completed, that is, identifying all of their stations, operating frequencies and schedules, the collection effort was not too difficult to maintain, despite changes by the Germans. In early September 1942, the police changed their callsigns, but not their frequencies or schedules. The Y-operators at Beaumanor were able to quickly equate the new and old callsigns within a few days.48

The other allied monitoring station that copied police and SS communications merits a short consideration because of its unique contribution to the intercept of Axis communications relating to the Holocaust, as well as the curious story of the site itself. P.C. Cadix (P.C. stood for Poste de commandement or command post) was a covert Allied intercept site located in the southeastern part of unoccupied Vichy France at the Chateau de Fouzes near the town of Uzes. The site was manned by a polyglot team of Poles, exiled Spanish Loyalists, Free French, and the occasional stray Englishman. The monitoring station originally had been formed in late 1939 by Colonel Gustave Bertrand, head of the French Army's radio intelligence organization, the section d' examener (S.E). In its initial configuration the site was first known as P.C. Bruno located near Paris, France.

Following the fall of France in June 1940, the team that had manned P.C. Bruno, after spending a short exile in Algeria, returned secretly to southern France. From October 1940 to November 1942, P.C. Cadix, as the site now was named, intercepted German high frequency communications in occupied France and elsewhere. Because of the peculiarities of HF radio propagation mentioned above — such as the interval of the angle of reflection off the ionosphere of the sky wave of a radio signal, known as the skip distance, and extended propagation of HF and lower frequency bands during the night — P.C. Cadix was able to monitor German radio traffic from the Russian front at night, and signals from Germany to the units during daylight. Because of this situation, Beaumanor and P.C. Cadix split the work on German Police traffic, with the British copying on even days and the French site working the police nets on odd days.49 Among the radio messages intercepted by Bertrand and his team were over 3,000 sent by German Police and the SS formations, many of which contained reports of the atrocities committed by these units.50 P.C. Cadix transmitted the decrypts by radio to Bletchley Park. Ironically, these transmissions were encrypted with an Enigma.51 Cadix continued to operate until late 1942 when it was forced to shut down, and its staff had to flee pursuing German security forces during the occupation of Vichy France that followed the Allied invasion of French North Africa.

It is a most important point to understand that the intercept of an Axis message was the initial step in the communications intelligence process. The quality of the intercept pretty much defined whether that message eventually could be useful for Allied intelligence. Radio reception conditions and the abilities (or lack thereof) on the part of monitors dictated the duration and difficulty of the subsequent analytic exploitation of intercepted messages, or even if the analytic effort could be started at all.

Step 3: Processing the Intercept

Once the enemy's messages were intercepted, and if they were not decrypted at the site, then they had to be forwarded to theater or national centers for processing. Generally, tactical military communications, that is, those between Axis units of division-size and below, were decrypted and translated at a large intercept site or at intermediate processing centers located in such places as Hawaii, Egypt, Ceylon, and Australia. Allied tactical field intercept units also could monitor, decrypt and translate low-level encrypted or plaintext enemy messages and pass them along to their immediate commands. So-called higher level cryptographic systems — and this meant all traffic encrypted by Enigma, Purple, and other machines as well as Axis and neutral diplomatic messages — were processed at the major analytic centers of Bletchley Park outside of London, Berkeley Street in London, England, OP-20-G Headquarters on Nebraska Avenue, N.W., Washington, D.C., and at Arlington Hall Station in northern Virginia.

Early in the war, intercept sites within the U.S. or U.K. sent the intercepted messages to the national centers over cable by encrypted teletypewriter. Overseas facilities sent their material by air transport. This meant that intercept could take weeks to arrive at a processing center. Later in the war, when enciphering communications equipment had been installed at major overseas intercept sites, the intercepted cipher text could be transmitted by enciphered radio or underwater cable to the national centers for decryption and translation. To securely transmit this intercept back to the processing centers, the Western Allies used their own high-level cipher machines, notably the British TypeX or the American SIGABA, both of which were considered unbreakable by Axis cryptologists.52

By war's end, this enciphered communications system linked most of the Allied intercept and processing centers together in a worldwide network that allowed intercept from a remotely situated monitoring site to reach the appropriate analytic center. In the United States, so-called traffic or signal centers were set up in Washington, San Francisco, California, and Seattle, Washington. These centers relayed the intercepted traffic from overseas stations via cable to the Signal Security Agency at Arlington Hall, Virginia. British or Commonwealth intercept destined for the SSA came from London through the British Security Coordination located in New York City. The BSC also relayed Canadian intercept from Ottawa, Canada. U.S. field stations as far away as Kunming, China, and Asmara, Ethiopia, could get their intercept transmitted to SSA Headquarters within a day via this series of radio and cable relays. The chart on page 37 from June 1945 illustrates the network.

Once the intercepted messages arrived at the centers, they were sorted by target country and service element. The copy was then distributed to the appropriate target country office for analysis. So-called traffic analysts performed the initial evaluation of message "externals." (The British referred to traffic analysts as "discriminators.") This traffic analytic process can be likened to the study of the outside of a mail envelope. Even without reading the enclosed correspondence of a piece of mail, the recipient's and sender's identity and addresses, the postmark, weight and size of the envelope, the postage class, special handling instructions, and the history of prior correspondence between the two can reveal much about the content of individual letters.

At Arlington Hall Station, analysts from the B-I section performed the initial review of the intercept. The externals they studied included parts of the intercept such as station callsigns, message precedence (or its urgency), message serial number, the number of recipients and relays (if used), and tips to the cryptographic system. These items were studied for clues to the content of the message and perhaps the identity of the ultimate recipient. For example, many diplomatic messages were sent to radio terminals with only the notation of the ministry for which it was intended, such as "Ministry of Foreign Affairs." If possible, the analyst would try to determine to which department the message was addressed. The analyst would review the files on previous intercepts to see if there were any clues that indicated the message's recipient.

From there, the message, or a copy of it, was routed to the appropriate code breaking office. At Bletchley Park, cryptanalysis was done at Hut 6 for military, air, police, and the SS, or at Hut 8 for naval traffic. The GC&CS site at Berkely Street in London received diplomatic and commercial intercepts. At Arlington Hall, the SSA cryptanalysts worked in section B-III, which handled all military and diplomatic intercept. The cryptanalytic task, the actual recovery of the message contents from its encoded or encrypted format, was a formidable one due to the enormous number of possible cryptographic systems employed by target countries. Allied codebreakers had to contend with almost 500 codes and ciphers.53 For example, British cryptanalysts worked against over 100 German cryptographic systems.54 Many countries employed numerous cryptographic systems. For example, France (including the Vichy, Gaullist, and Giraudist factions) used over 100 systems for its armed forces, diplomatic, and colonial communications. Switzerland had available over ten manual systems and a simplified version of Enigma just for its diplomatic messages.55 Not all countries used all of their systems all of the time. Some systems were reserved for messages of certain levels of importance. Some military or naval encryption systems were designed for use by a single command or region. For some countries, most of their communications were encrypted using relatively few systems. For example, although the Vatican was known to have nine diplomatic systems available for its apostolic delegates, it used only three systems, and one of those was so seldom used by the Vatican that American and British codebreakers could make no progress against it.56

It has been popularly portrayed that Allied cryptologists often could read enemy messages before the intended recipient. In a few instances this was true, such as occurred with some Purple decrypts prior to Pearl Harbor. Generally, though, this capability was rare. The ability to exploit encrypted traffic in a reasonable time after intercept was possible only after the cumulative application of physical resources and months of human analytic effort devoted to a single system such as Purple or the constellation of Enigma variants.57 Allied cryptologists did not reach that level of expert or timely exploitation for all Axis cryptographic systems.

Another aspect to the cryptanalytic process was the constant risk that Axis cryptographers would change or replace current codes or ciphers that the Allies were exploiting. This danger existed for all major Axis cryptographic systems. There was a notable example of this in January 1942 when the German Navy replaced the three-wheel Enigma used by the U-boats with a newer four-wheel version. As a result of this move, the Allies were unable to exploit U-boat messages encrypted in the new Enigma until November 1942. In another example, in September 1941 the German Police began to change over its current manual encryption system, a double transposition cipher to another, a double playfair.58 This change was completed by early November. The playfair was quickly broken; in fact it was a simpler system. This switch illustrates the inherent risk that faced Allied codebreakers every day during the war.59 (See pages 49-50 for more on the background to this change.)

It is also true that not all foreign cryptographic systems warranted the same level of cryptanalytic effort that had been made against the Purple machine or the various versions of the Enigma. There were a number of reasons for this. As pointed out above, there were quite a number of systems to attack, far more than the number of available cryptanalysts. For many systems, including manual codes and ciphers and some machine systems, not enough intercept was acquired to allow for their successful or timely cryptanalysis. Depending on the systems' complexity and potential for intelligence, some codes or ciphers would be exploited relatively quickly; others, because of their difficulty, took a great deal of time and resources to break. For example, the high-level German diplomatic systems, known as Floradora and GEE, took, respectively, four and five years for Allied codebreakers to solve.60 A few machine cipher systems, such as the German Gestapo Enigma, known as TGD, defied Allied cryptanalysis completely during the war.61

The British had a large section in Hut 6 at Bletchley Park devoted to the decryption of the police ciphers. There were good technical, cryptologic reasons for this extensive effort. The texts of decrypted police messages sometimes provided cribs — plain text assumed to be present in enciphered messages — to those messages encrypted with the Enigma by other services such as the Wehrmacht. Also, many Wehrmacht and Luftwaffe operational units retained reserve manual ciphers similar to the police system in case of Enigma failure, or used them for messages of a less importance.62 As for intelligence value, the police messages were important because they provided information on much more than the massacres of Jews and other groups in Russia. They contained information about economic, political, and social conditions in Germany and occupied Europe, the suppression of resistance groups in the conquered countries, the political situation in Italy after the fall of Mussolini, news of Allied POW escapes, the effects of Allied bombing on the morale of German civilians, and the SS plunder of art and other cultural items from other countries.63

For systems that had been broken, there was virtually no retroactive effort by the Allied cryptologists to solve so-called "back traffic." For example, there was no plan to go back and read the high-level German diplomatic messages that had accumulated prior to the cryptanalytic breakthroughs in 1944 and 1945. In another case, by early 1944, the War Department's Special Branch conceded that there was no way that some 200,000 intercepted Japanese military messages, encrypted and encoded in systems that were now exploitable, which had been stock-piled, would ever be read by the Army. Arlington Hall conceded that there was too much current intercept arriving from the field and just keeping up with that flow negated any chance for work on the old messages. Also, the Army's analysts had to stay on top of the current systems in case the Japanese changed them. The author of a memorandum reviewing this situation at Arlington Hall could only muse about how much "priceless intelligence" was lost. 64

How much of the total intercept ultimately was exploited cryptanalytically is not known. There is no quantitative data about how many possible messages may have been missed (or copied too poorly for use by the code-breaking sections). There is not much data about intercepted messages encoded or encrypted in cryptographic systems that were unbreakable. Likewise, there is little statistical information available to determine an overall success rate for Allied codebreakers. The few records with statistics concern how many messages were intercepted and how many were broken. If the incident about the Japanese Army messages related in the preceding paragraph can be used an indicator, then it is possible that a substantial number of messages were intercepted but not exploited. In reality, the general rate of successful decryption or decoding of intercepted messages may not have been particularly high, and this estimate includes messages that were partially exploited. For example, in fiscal year 1944, the Allies intercepted about 576,000 Axis and neutral diplomatic messages. The SSA cryptanalytic branch at Arlington Hall, B-III, managed to solve about 89,000, or a rate of slightly less than 15.5 percent.

This low rate, though, does not mean that the Allied codebreakers failed to produce intelligence. For one thing, the priorities established by the Allied staffs ensured that the communications most important to the war's prosecution received the most coverage and analytic attention. Axis military systems, such as U-boat Enigma traffic, were exploited in much larger numbers and a greater rate relative to intercept than targets of lower interest such as neutral diplomatic networks.65 As for the diplomatic problem, the major targets of interest, Japanese embassies in Axis and neutral capitals were the highest priority and accounted for approximately 54 percent of all diplomatic translations.66 Success for the Allied cryptologic effort must be measured in the intelligence gathered that affected the course and outcome of the war. Still, the general result of the codebreaking was that a relatively small percentage of the intercepted messages were available for the next set of analysts — the translators.

Translations of the decrypted high-level Axis and neutral messages were done at Huts 3 (military and air) or 4 (naval) at Bletchley Park, at Berkeley Street in London (diplomatic and commercial), and at the B-III section of Arlington Hall Station. A translation took a few steps to complete. Initially, a linguist would complete a worksheet. Usually this took the form of the decrypted text with a word-to-word translation. Next, the linguist would compose a draft English text based on the worksheet. A final version of the text would then be written. Usually this form carried any comments considered necessary for the reader of the translation. For example, if a particular passage proved to be difficult and open to other interpretations, that bit of text in the original language would be included in a footnote.

The translation problem facing the cryptologic agencies was enormous. The nature, size, and logistical needs of the language problem proved to be as daunting as that of decryption. The target countries, Axis, minor allied, and neutral, used three-dozen languages. The mixture was an almost devilish variety that ranged from relatively familiar European languages, such as French, German, and Spanish, which were taught at many American and British schools, to the unfamiliar and rarely taught Amharic, Arabic, and Thai.67

At the beginning of the war, one of the major issues confronting the Allied cryptologic organizations was that they had to produce a large enough cadre of linguists to handle the range of languages found in the decrypted messages. This early lack of translators created a bottleneck in the processing of intercept. For example, during the month of March 1943, SIS had received over 114,000 intercepts, mostly Japanese Army, but also weather and diplomatic messages. Yet, Arlington Hall could produce only 4,500 translations. The problem was a lack of translators to handle the load.68

Once training programs were running and producing linguists, other problems intruded. Again, wartime priorities often defined the direction of the linguistic training effort. For the Americans, Japanese was the language emphasized in its training programs. This emphasis was driven partly by the division of effort with the British, though the latter had their own Japanese training program. Other languages of interest were not ignored, but American linguistic training was dominated by the needs of the war against Japan. Besides the dominance of Japanese language needs, another problem was other organizations that competed with the cryptologic agencies for these rare linguists. The most important was the Allied Translator and Interpreter Section (ATIS), which performed critical roles such as POW interrogation and translation of captured enemy documents in all combat theaters.

Once the linguists were assigned to analytic centers, their work was supposed to be verified at various steps for correctness and readability. Nonetheless, the quality of translations the cryptologic agencies produced during the war varied. In the archival record collections, researchers easily can find numerous excellent translations, and many with serious shortcomings in grammar, syntax, and vocabulary. Many of the problems probably arose from technical gaps in linguistic resources. Linguists not only had to become proficient in a language, as they went along in their work they had to learn or develop specialized glossaries for military, nautical, and aerial jargon, equipment references, and so on.69 The text of diplomatic messages often contained exactingly precise language that was difficult to render into equivalent English. Many diplomatic messages reported conversations and interviews with individuals that had been translated from the language of the host country. Also, messages were composed with a background context that assumed a prior understanding between original sender and intended recipient. If the linguist had not seen any previous messages, allusions to other individuals, issues, and the significance of topics in the text could be opaque to an Allied translator. For the recipients of the translations, though, these shortcomings may have not always posed a problem: the main ends to translation were availability and utility, not elegance and erudition.

The rapidity at which a translation could be completed varied, as well. The above difficulties affected the turnover from decrypt to translation. Further, if an intercept was considered important, and the decryption could be done quickly, it would be translated relatively quickly. If not, it could be some time before a translation was completed and disseminated, perhaps weeks or even months. An example of this difference can be illustrated by two diplomatic intercepts of late June 1944 from Budapest. Both messages had been received at Arlington Hall one day after being intercepted by the U.S. Army's monitoring station in Asmara, Ethiopia (MS-4). The first intercept was a 26 June 1944 Hungarian diplomatic message to Ankara, Turkey, that reported world reaction to the initial roundup of Hungarian Jews. It took Arlington Hall from 27 June to 16 December 1944 to complete its decryption and a formal translation to be issued — almost six months. The second intercept was of a Vichy diplomatic message from Budapest to Ankara, Turkey, that reported the situation of a group of Lebanese Jews trapped in Budapest. It took Arlington Hall from 13 June to 24 June to decrypt and translate this message, or only eleven days.70

The specific reason (or reasons) for the long delay in issuing the translation of the Hungarian intercept is not known. The quick processing of the Vichy intercept probably can be explained by the long familiarity of Arlington Hall analysts with Vichy diplomatic cryptographic systems that had been solved about two years earlier, as well as the comparatively easier French plain text. The delay in processing the Hungarian intercept suggests more difficulty with Hungarian cryptography, as well as problems with the Magyar language. The long processing time for the Hungarian intercept does not mean that information of intelligence value it may have contained would have been held back until a full translation was done. In a heat of operational necessity, intelligence could be passed informally.

At the beginning of the war, the United States cryptologic agencies were producing only a few separate series of translations, notably the diplomatic series by the SIS and Japanese Navy translations by OP-20-G. These early series of translations suffered from a number of limitations. There were too few being written; they were not timely; and the translations suffered from missing portions of text. As the war progressed, both army and navy code- breakers got better at breaking Axis and neutral cryptographic systems, and began to exploit more systems. As the number and variety of readable intercepts increased, the number of resulting translations also grew.

The initial translation series proved to be inadequate to handle the growing flood of intelligence. The analytic centers created additional specialized translation series that were categorized by topic, source, or administrative needs. By the end of the war, the U.S. cryptologic elements were producing over sixteen separate series of translations. Some were for a general intelligence audience, such as the Japanese military translations. Others were for the cryptologic elements themselves. These series usually carried the notation "CI" for "Code Instruction." Most of the translation series had no or very little information about the Holocaust beyond a passing reference. The two that contained the most information were the "H" (Multinational Diplomatic) and the "T" (Reserved, or Restricted Diplomatic) series.71 These two series are discussed in some detail in Chapter 3, pages 61 to 64. The British created fewer translation series compared to those of the SIS.

Although a precise accounting of the final tally of finished translations produced by the Western cryptologic agencies is beyond this study, it should be pointed out that the intercepts that were translated represented only a part of what previously had been decrypted, which, in turn, was a portion of what originally had been intercepted. Even by the end of the war, the overall rate on some targets was still relatively low. In July 1945, an Inspector General survey of OP-20-G activities indicated that only 10 percent of all intercepted Japanese naval messages were being fully processed and disseminated to the various military commands.72 Recall that the number of decrypts produced by B-III in 1944 was 89,000 (out of 576,000 intercepts, or 15 percent); the estimated number of translations for the same period is about 50,000. This represents about 56 percent of the decrypts, but only 8.6 percent of all diplomatic intercepts.73

The 1944 American total of diplomatic translations issued is surprisingly close to that of GC&CS at the start of the conflict. In 1940 the Diplomatic and Commercial Section of GC&CS reported that it had received (intercepted by radio or cable, or acquired through espionage) 100,000 telegrams, read 70,000 of them, but circulated only 8,000. The British numbers also represent another aspect of this problem mentioned earlier: the relative dearth of intelligence of importance that was contained in the intercepted messages. The low figure of translations disseminated through the British government, some 8 percent of all intercepts despite a 70 percent success rate of decryption, suggests that many messages that London intercepted contained little intelligence of importance to the prosecution of the war. The intercepts were largely of minor neutrals and allied governments in exile.74

Once the translations were completed, other intelligence analysts reviewed them for usable information. At Hut 3, this work was done in the indexing sections. These individuals, many of them women, extracted those elements of intelligence that contributed to the larger information matrixes that were important to the war's prosecution — order of battle, equipment listings, names of individual officers, etc. At Hut 3, a senior indexer would flag the information that needed to be entered into large index card catalogues for further use. The information was entered onto index cards, cross-referenced, and stored in cabinets within Hut 3 for future reference.75

No information was overlooked. Even that data that appeared innocuous and subsequently not important by the Axis, could reap benefits from good indexing. For example, prior to the war, the British intercepted messages from the Italian Air Force in North Africa. The messages contained seemingly mundane information: specifics about repairs of the engines to Italian aircraft. Many of the messages listed engines by serial number. Alert British analysts compiled these serial numbers. The payoff was that, by knowing the status of almost every aircraft engine, the British could develop a complete picture of the size, composition, and availability of aircraft to the Italian Air Force in North Africa when hostilities began in September 1940.76

Step 4: Disseminating the COMINT

Once a translation was completed, there remained the problem of getting the intelligence it contained to the military and civilian leaders and organizations that needed it. In Britain, the Joint Intelligence Committee, which served under the Chiefs of Staff, produced intelligence reports for the rest of the government. The JIC had been functioning since before the war (when it had been called the Joint Intelligence Subcommittee). The major services and Foreign Office were represented on it. The services and the Foreign Office, which was responsible for M.I.6, and, ultimately, GC&CS, funneled intelligence to the JIC, which, in turn, distributed it to the necessary recipients. The JIC also issued the military, political, diplomatic, and economic estimates of the war.77

Early in the war, the United States SIS produced and disseminated COMINT to other agencies and commands, usually in the form of translations. This system soon broke down. The Army codebreakers were swamped by the increase in messages to exploit. SIS was unprepared organizationally and lacked the resources to distribute the COMINT. It reported communications intelligence in a haphazard fashion; no effort was made to check the signals intelligence against other sources. Organizationally, the SIS remained within the Signal Corps. Its product had to go to G-2, the War Department's intelligence arm. Another organization, the Special Branch, was formed in mid-1942 under the control of the War Department's operational intelligence arm, the Military Intelligence Service. Special Branch thereafter would handle the analysis of the COMINT product from SIS, combine it with other sources of intelligence, and then disseminate to the rest of the government whatever useful intelligence it had gained. Special Branch produced the "Magic" Summary and also other special topical studies.78 In 1944 Special Branch was broken up and subsumed under the War Department's Military Intelligence Service, which took over the management of COMINT analysis and dissemination.79

Within the British government and ministries, the Ultra material was distributed to the intelligence and service ministries that required it. As a general rule, copies of all Ultra translations or decrypts were sent to Secret Intelligence Service Headquarters in London and the intelligence departments of the three services. This distribution scheme varied, though, as the war progressed. A good example of this change can be seen with the dissemination of the German Police decrypts. For example, in August 1941 eight copies of police decrypts were produced and distributed. One copy went into the files. Two copies went to M.I.6 HQ, while another was transferred from the Service to the Ministry of Economic Warfare. A fourth copy went to the Air Ministry intelligence section. The fifth copy went to M.I. 8, British Army Y staff. The War Office section responsible for occupied Europe, M.I. 14, received a copy. One final copy was sent to Bletchley Park as part of a standing intelligence exchange, known as the B.P.I.E.

Starting in late 1942, the police decrypts carried a distribution list that contained both office designators and named individuals within M.I. 6 or the intelligence section of the Air Ministry or War Office. Why the distribution became name-specific is not clear, though it may have reflected a maturing topical specialization by individual analysts within M.I. 6 and other ministries. Also, after 1943 it appears that copies of the police decrypts, including those of the SS, were passed to the American contingent at Hut 3 in Bletchley Park. For example, in August 1944, a Lieutenant Colonel Taylor, most likely Lieutenant Colonel Telford Taylor, the G-2 Special Branch representative to Bletchley Park, received a copy of an SS message detailing the rail transport of almost 1,300 Jews from Hungary to Auschwitz.80

For the Allies, this last step in the communications intelligence system potentially was the trickiest because it was the one most likely to compromise Ultra to the Axis. It was recognized early in the war that such information, being at once the best source for Axis plans, intentions, and capabilities, also could be the most ephemeral of all intelligence sources. To lose the advantage that Ultra conferred on the Allies — what Churchill on one occasion called his "golden eggs" — could have been critical to the progress of the war, if not to its outcome. This was especially true in the early years of the conflict when Ultra was just about the only edge that a beleaguered Great Britain had against the military and naval forces of Germany and Italy in the various combat theaters. A method was needed to allow access to the intelligence derived from Axis communications, known variously as "Boniface," "Most Secret Source," or Ultra, to those who had the "need to know," especially in overseas commands. Yet, that method had to ensure that the cryptologic sources would not be compromised and subsequently lost.

To solve the security problem posed by disseminating Ultra to overseas commands, the British developed a system to control the distribution of COMINT and, concurrently, to minimize the chance of its exposure. In August 1941 an organization, the Special Liaison Units (SLU), was formed under the control of the Chief, Secret Service, that administered the dissemination of Ultra to British commands in the Middle East. Soon, SLUs were present at every command of the British armed forces. These units were staffed largely by Royal Air Force personnel who were familiar with the signals intelligence sources and could offer technical background information concerning the intelligence. The unit also enforced the security regulations that protected the Ultra intelligence.

The units, many of which were attached to the various Allied commands around the world, received the Ultra intelligence from Hut 3, most commonly in the form of a translation. The intelligence was transmitted by enciphered radio, cable, or carried by a courier. When normal communications service was not available to an SLU, the transmission of Ultra information to the field was handled by Special Communications Units (SCU). The translation, or the message that contained it, carried a special designator (two- or three-letter combination) known as a delivery group that specified the recipients. A single translation could carry several delivery groups depending on how many commands had the "need to know."81 The SLU, in turn, dispatched special representatives who delivered the information to those individual commanders, ministry heads, and diplomats cleared to receive it.

Keeping the lists of recipients approved, or "cleared," to receive Ultra was another facet of the SLU system. The lists were fairly limited; recipients usually were high-ranking ministers or military officers, generally no lower than corps commanders or their equivalents in the other services. For example, in the United Kingdom, a late 1944 Ultra distribution list for the Supreme Headquarters Allied Expeditionary Force of cleared army and air force personnel ran some twenty pages and included about 500 names.82 Yet, when one considers the size of SHAEF, and the subordinate commands involved, this listing is not particularly large.

The Americans developed their own version of the SLU, called the Special Security Officer or SSO. The SSO system was sponsored by the War Department's Special Branch and officially was adopted by the War Department in late 1943 as the main method of Ultra distribution to major U.S. commands. The SSO liaisons were first established in the Pacific, Southwest Pacific, and China-Burma-India Theaters. Eventually, by spring 1944 an SSO was set up in Europe to support General Eisenhower, although an SLU counterpart also was present. Like their SLU counterparts, these officers personally handled all aspects of the Ultra traffic. They received the intelligence messages sent from the War Department, carried the intelligence to their designated recipients, briefed them, and then returned with the material.83

The other major American system of distribution of communications intelligence was by summary report. This distribution method began with the early typewritten "Magic" Diplomatic Summary and was published first in March 1942. The summary remained limited to senior officials within the Washington, D. C., area: the White House and the War, Navy, and State Departments. A subordinate office of the Special Branch of the Military Intelligence Service compiled this summary. It was a digest of relevant translations based mostly on diplomatic sources with a preponderance of Purple, or Japanese diplomatic translations. Some other sources of information included mostly prisoner debriefings and digests of reports from aerial imagery. Occasional press and OSS-produced intelligence sometimes would be slipped into a summary, but COMINT material clearly dominated the content of the summaries, sometimes comprising over 90 percent in a single issue. Occasionally, communications intelligence was the only source in a summary.84 It was understandable why this was called the "Magic" Diplomatic Summary.

With the closer liaison between GC&CS and SIS, and the resulting access to more intelligence, the number of American summary reports grew. A European version, the "European Summary" was started in late 1943. Special Branch representatives in Britain culled Enigma translations published by Huts 3 and 4 for items to include in this summary. The European Summary was based mostly on translations of Axis military intercept. Also, the distribution of the European Summary was limited to about a dozen copies sent to Washington.85 Except for two examples, a complete set of this summary series has yet to be located in any archival holdings in the United States. In July 1944 a "Far East Magic Summary" was started. It summarized the military, political, and diplomatic Magic translations and military intelligence reports related to the campaign against Japan. It was published through the surrender of Japan in September 1945. 86 This latter summary carried no information on the Holocaust.

Access to the "Magic" Summary was limited, usually with only a few copies hand-carried to the War, Navy, and State Departments, and the White House. The service chiefs, General George Marshall of the Army and Admiral Ernest King of the Navy, saw them, as did their deputies for intelligence and operations. Secretary of State Cordell Hull and the Assistant Secretary of State, Adolph Berle, received the summaries. Whether the copies of the summary were returned immediately to Arlington Hall when reviewed or held in a secure area for a short period is not clear. Whatever the case, it appears that the copies of the summaries eventually were returned to Special Branch.

How much communications intelligence reached the "top," that is, the desks of Prime Minister Churchill and President Roosevelt, depended both on their individual predilection and the selection process by their staffs. Churchill has been portrayed accurately as a voracious consumer of Ultra information. In September 1940 Churchill requested that "C," Stewart Menzies, the head of M.I.6, provide him daily all Enigma messages.'87 This request clearly was impractical because of the number of decrypts. By summer of 1941, Churchill was receiving a daily brief from "C" that summarized important Ultra material. Bletchley Park produced a veritable daily banquet of information from which Churchill simply feasted. Sprinkled throughout the daily briefings are reports about the massacres of Jews in Russia, Hitler's directive to shoot German political refugees taken prisoner with Free French units, Jewish internees in North Africa used to unload Axis ships in Tunisia, anti-Jewish hostility in Turkey, Himmler's instruction to the SS to remove all works of art from Florence, Italy, rumors of the German Reichsbank hiding gold and sensitive documents, and SS orders to move Jewish inmates to Dachau late in the war.88

Churchill used the intelligence from the daily briefings for planning strategy and berating commanders who were slow to exploit local advantages that he saw from Ultra decrypts.89 At these briefings he also was informed of sensitive political and intelligence issues, such as the danger of passing Ultra to the Soviets, increasing German signals security, and the chance that Ultra might be compromised by a "precipitous" military action against Field Marshal Erwin Rommel's Headquarters.90 The daily summaries he received from Bletchley Park during the war, as contained in the PRO series HW1, illustrates the depth and breadth of the intelligence brought to his attention.

On the other hand, FDR seems to have been living on, if not quite a monk's diet, then certainly a somewhat leaner ration when compared to Churchill's appetite for Ultra. It was not that Roosevelt was uninterested and ignored the intelligence from radio intercepts. He referred to the Purple translations closely during the failed negotiations with Japan prior to Pearl Harbor. He did, in fact, continue to receive this intelligence in various forms throughout the war. The most notable was the "Magic" Summary. Roosevelt's aides would brief him in the morning or afternoon (or both) on the highlights from the various summaries. The White House also received "translations of interest" from either the Army's Signal Intelligence Service at Arlington Hall or Special Branch throughout the war. Sometimes he would ask to read some of the translations used in the summary. All of his aides have reported that the president was extremely well informed from the intelligence. Usually when the president went abroad to conferences, such as Casablanca and Cairo, the Magic material was forwarded to him.91 And FDR would complain about a lack of intelligence on a particular issue he found important. For example, in November 1943 he called the secretary of war, Henry Stimson, and the secretary of the navy, Frank Knox, to the White House to complain about a lack of intelligence on the domestic and political situations inside Japan.92

It appears that other U.S. officials were not always satisfied with the distribution of "Magic" information to the president and his use of it. General George Marshall, who well understood the importance of the COMINT, established a new summary system in early 1944 for President Roosevelt, creating a presidential "Black Book" of briefings. He did this after discovering that FDR was not getting or reading the Magic decrypts from the Army. In February 1944 he addressed a memo to President Roosevelt specifically on this issue. In the first paragraph he reported that he had learned that the president "seldom sees the Army summaries of ‘magic' material." Marshall later explained that a new arrangement of material had been prepared and that the president should avail himself of these.93

It is difficult to determine the precise context for Marshall's complaint. FDR was receiving intelligence daily, indeed even on occasion demanding it. Marshall may have believed that Roosevelt was not utilizing "Magic" when making wartime decisions. Certainly, Roosevelt's approach to wartime leadership differed substantially from Churchill's. Unlike Churchill, who hectored his generals and admirals for action and often used Ultra as his hammer, FDR left the execution of the war to his military chiefs. Roosevelt preferred a personal working relationship with his commanders. They would develop and carry out operations subject to his approval. As long as his military commanders kept FDR's confidence, they were free to direct the military operations of the war. Perhaps to a person of Marshall's business-like attitude, FDR could appear maddeningly casual or detached from the direction of the war, especially when compared to Churchill's tendency to get involved to the point of almost meddling.94

A review of the "Magic" Diplomatic Summary files shows that they contained very little information about Axis atrocities or crimes against Jews or other groups in occupied Europe. There were perhaps three or four items a year beginning in mid-1942.95 Additionally, from the set of translations SIS forwarded to the White House from early 1942 to the middle of 1945 only one — an Irish diplomatic message from Rome in October 1943 — can be found that had anything to do with the Holocaust.96 Whether these few reports from American signals intelligence on the Holocaust eventually were briefed to President Roosevelt is unknown. This small number of references in the summaries is interesting because U.S. COMINT produced over 400 translations dealing with aspects of the Holocaust. Almost all of these were from diplomatic sources. Also, it seems that Roosevelt never saw the German Police decrypts that GC&CS had produced earlier in the war.97 This gap, though, may be explained by the fact that the German Police and SS mostly had stopped reporting by radio about the massacres in Russia and the concentration camps by the end of 1942. Whether he was apprised of the information in the British decrypts through other sources, possibly the OSS via its exchange with the British Security Committee in New York, is unknown. The president had other sources of information about the Holocaust, including the OSS, his advisors, like Rabbi Stephen Wise, and personal briefings from first hand observers like Jan Karski.98

Throughout the war, President Roosevelt’s reaction to the news of the Holocaust could be characterized as sympathetic, but also as realistic and restrained. He did authorize the Allied Declaration condemning the Nazi killing of the Jews in late 1942. He also publicly denounced the Nazi execution of civilians in October 1941. The president favored the postwar retribution against Axis war crimes. Yet, he believed that the best course to end the killing was the successful and quick defeat of Nazi Germany.99 Furthermore, Roosevelt, like Churchill, understood the political problems that would follow from any statement that singled out Nazi atrocities against the Jews. The Germans could very well use any specific declaration about the Holocaust against the Allies as a propaganda weapon. And, on occasion, they did, denying claims about gassing of Jews and publicizing stories about Jewish control of the Allied war effort.100

There was also an overriding security consideration regarding the dissemination of Ultra material about the Holocaust. Publicizing any information based on Ultra could seriously compromise the work at Bletchley Park, especially the exploitation of the German high-level Enigma and its many variants. If the Germans had been warned that the Allies had penetrated their most secret ciphers and codes, they could have installed new systems. Allied codebreakers then would have been returned to the difficult early days of the war when Enigma's workings were a mystery. If such a compromise had occurred in 1941 or 1942, the attendant loss of information could have adversely affected the Allied strategic posture against Germany.

The fear of compromise of Ultra sources rightly dominated and formed the entire British (and later American) administration of the dissemination of intelligence derived from it. The Allies developed some ruses and cover stories to protect these sensitive cryptologic sources.101 The initial British approach to disguising Ultra material was to make it appear to have originated from a traditional espionage or agent source. The original cover name for Enigma decrypts was "Boniface," and the material from Bletchley Park was issued by M.I.6 to further disguise its source. This cover name was used to suggest that the information came from an agent high in the German command that was controlled by M.I.6. This approach may have secured the cryptologic source, but it often subverted the impact of the Ultra material since many recipients were skeptical of what they assumed was human agent information. But the British leadership appeared to accept the loss of some operational efficiency as long as security was maintained.102 By late 1941, though, the volume of Enigma decrypts had increased dramatically as had the number of recipients. This growth forced the British to finally extend the initial SLU presence in the Middle East and give more recipients the "need to know" about the source of Ultra intelligence.

While this expansion of approved recipients solved one aspect of the security problem, it still left the problem of compromise of Ultra information through its use in military operations. When there were no other intelligence sources to account for knowledge of Axis plans and moves, the Allies had to devise ways to disguise the role of Ultra information. An example of this was the British use of reconnaissance aircraft flights to "discover" Axis convoys in the Mediterranean that were known already through Ultra. When British codebreakers learned the date and route of an Axis supply convoy, the Allies would schedule many days of air reconnaissance over the route.103 In the Pacific, the aerial ambush of Admiral Yamamoto in April 1943 had been based on a decrypt of the valuable Japanese naval code, JN-25. The cover story, told to the U.S. Army Air Force pilots who carried out the mission in case they were captured, was that the information on Yamamoto's flight came from Allied coast watchers.104 In another interesting example, shortly after the German invasion of the USSR, the British supplied the Russians with signals intelligence based on high-level cryptanalysis. However, London was aware that the Germans could exploit many Soviet ciphers and that Berlin could discover Ultra information in Moscow's radio traffic. Therefore, London disguised the Ultra it gave Moscow and characterized it as "a most reliable source."105 In all of the above cases, a subterfuge was used to cover the real source of the information. Still, no matter the deception or cover for the real source of information, there was always a chance of discovery by the Axis. And this fear weighed heavily on the Allied codebreakers.

The handling of the information derived from the German Police decrypts from the Russian front in the summer of 1941 points to the dilemma just discussed. On 24 August 1941, Winston Churchill delivered a radio speech about the atrocities committed by the police on the Eastern Front. It was based on information derived from police decrypts. The prime minister was aware of the German depredations against Jews and other target groups in Russia since the start of the invasion. He may have been motivated to make the broadcast because of the shocking information in the reports. In the radio address, Churchill mentioned that Russian inhabitants from entire districts were being exterminated, but he made no reference to Jews being a specific target of the police units. Instead, Churchill made a general statement about German Police executing Russian "patriots." Perhaps in the first months of the invasion, the prime minister had not yet understood the emphasis on the Jewish target by the police and SS.106

Even though the sole source for British know-ledge of the massacres in the western Soviet Union was the police decodes, it appears that Churchill was not sensitive to the potential for compromise when he included a reference to the police executions in his broadcast. Nor is it certain if senior officials of M.I.6, GC&CS, or the Joint Intelligence Committee were themselves sensitive to the possibility of a compromise of the police decodes. Churchill may have viewed the military situation in August on the Russian front as critical. Certainly, there were members of his cabinet who believed that the Soviet Union was facing defeat.107 He may have wanted to bolster domestic British support for Moscow's struggle by delivering the speech.

A probable result of Churchill's speech was that, on 12 September 1941, Kurt Daluege, the commander of the German Police units, sent a message to all of his command to cease transmission of reports by radio of the mandated executions on the Russian Front. A second probable effect of Churchill's speech was that, in November 1941, the police changed the manual encryption system for their messages from a double transposition cipher to a double playfair system, the latter of which, ironically, was a relatively easier system for Bletchley Park to exploit. The British cryptologists believed that Daluege's order and the cryptographic change were inspired, in part, by Churchill's broadcast.108 Although the order to cease reporting by radio had been sent on 12 September, nearly three weeks after the broadcast, it is likely the speech influenced the German changes. Daluege's 12 September order probably was preceded by a period of deliberation within the police leadership and staffs in Berlin about the practice of radioing reports of massacres. Not to be overlooked as a possible influencing factor, as well, is that Daluege's order may have reflected a long-standing concern with the cryptographic shortcomings of the police cipher and that the speech was the impetus for a final decision to rectify a long-standing cryptographic security issue.109

The dissemination of information derived from Ultra sources presented a constant security risk for the Allies during the war. The compromise of this capability, that is, of the cryptanalytic exploitation of any of the high-level Axis cryptographic systems could have closed a valuable source of information. Churchill's speech condemning German atrocities in Russia, by referring to the role of the German Police, contained a reference to the source of intelligence that may have tipped the Allied advantage in this one case.110 And it appears that the Germans quite likely changed their cipher in response to the prime minister's broadcast. That the Germans replaced the then current police manual cipher system with one easier to exploit was a matter of good fortune for the codebreakers at Bletchley Park; the opposite, that is, the replacement with a stronger cipher system, was just as likely an outcome. The reliance on intelligence from singular cryptanalytic sources such as Ultra only increased the potential for a major compromise of the Allied codebreaking. For the Allies, no matter the demands of the situation, whether it was countering an Axis military operation or revelations about the police massacres, the best security policy to follow was to avoid risking the disclosure of their cryptologic secrets throughout the war.

In October 1942 the British began to accumulate information on war crimes by the German Police units to be forwarded to the Foreign Office, which would keep the dossier. This arrangement had been agreed upon between Sir Alexander Cadogan, the permanent undersecretary for foreign affairs and the head of M.I.6, Stewart Menzies, following a suggestion by Sir Victor Cavendish-Bentick, who chaired the Joint Intelligence Committee.111 Two Foreign Office officials were to gather the information. How it was to be organized is not certain. Notes attached to the police decrypts suggest that the evidence was to be organized into three categories: (a) the number of people shot or maltreated in known and unknown areas, (b) officials responsible with summary of atrocities each had perpetrated, and (c) a listing of Police, SS, and Army units and a summary of the atrocities each had committed.112

At war's end, the Foreign Office had gathered together a number of Police and SS decrypts. In late May, Cavendish-Bentick approached Menzies about the classification of the material and whether that would mean it could not be turned over to the Nuremberg War Crimes Commission. Menzies passed the request to Edward Travis, the director of GC&CS after 1942. The response from Travis was that the Police decrypts that contained information about the massacres and other atrocities in Russia was "medium-grade" and could be released to the prosecution at Nuremberg. (The category was known as PEARL, referring to material derived from low-level cryptanalysis such as the manual ciphers used by the Police. This category was later recast as PINUP and included everything NOT derived from high-level cipher systems such as Enigma.) Travis added that the concentration camp messages could not be released because they contained some SS Enigma material, known as "Orange."113

This material, though, was never used at the Nuremberg War Crimes Trials in the prosecution of major or other criminals. Many Police officials were included in the group of lesser criminals, or Category 2, and some of them were tied to atrocities in the decrypts.114 Another striking feature with regards to the absence of the decrypts in the Nuremberg evidence was that the head of the staff for the American prosecutor, Chief Justice Robert Jackson, was none other than Colonel Telford Taylor. Prior to the trials, Taylor had supervised the exchange of Ultra material with the British from 1943 to 1945. As part of the BRUSA Agreement in June/July 1943, Taylor probably had received copies of Police decrypts from later in the war.115 But he most likely did not receive copies of any Police decrypts from prior to the agreement.

Taylor had worked at accumulating evidence against Axis war criminals for two of the general counts against the accused, that is, crimes against peace and crimes against humanity. Considering that some of the material, namely, the lower-level decrypts such as those of the police, could have been used as evidence, the failure by Taylor to utilize the material seems to demand an explanation. This is especially pertinent since one possible result of this unwillingness to use the decrypts was that many Police junior officers, noncommissioned officers, and rank and file police were not investigated for war crimes immediately after the war.116

There are probably two explanations for why the decrypts were not used by any of the Nuremberg tribunals. The first was that, according to Taylor, sufficient evidence already existed in the forms of captured documents, eyewitness testimony, and the depositions of the accused senior Police and SS officials. Taylor also deferred to the British, who, he contended, had more expertise about German organizations such as the Police, the SS, and others.117

The second reason, and perhaps the more compelling one in light of the ensuing thirty-year cloak of secrecy that dropped around Ultra, was the overriding concern by both British and American intelligence officials to keep secret the advantage gained from the wartime exploitation of high-level German cryptography. In the immediate postwar situation in Germany (and later for Japan) intelligence officials in both countries were concerned about resurgent national feelings or the chance that underground resistance movements might start up against the occupation governments. The Allies could suppress such potential movements by exploiting any ciphers or codes that might be used by the insurgents.

Also, the Western Allies took the long view when it came to protecting Ultra. New threats to world security could arise in the future. If there were a general awareness of the Allied success in codebreaking, then any future enemy would be on guard against the possibility that its communications might be exploited, and this would hamper any American or British effort against them.118

From Intercept to Decryption — the Story of One German Police Message

How the COMINT process functioned can be illustrated with an example of this German Police message of 16 June 1942 from commander of the Police in central USSR to Reichsfuehrer Heinrich Himmler and the Chief of the Order Police, Kurt Daluege in Berlin. The message, Nr. 14, was sent from Mogilev (callsign "SQF") in Byelorussia to Berlin (callsign "DQH") on 16 June 1942. The message was intercepted on 3742 KHz at 9:51 PM (GMT) at the British Army intercept site at Beaumanor (BMR) by shift operator "A115." The handwritten changes to certain characters in the cipher groups indicate that the operator had difficulty in copying the message. Another message was sent some time after "14," but the operator was unable to copy it due to man-made interference that is notated as "QRM." The interference could have come from inadvertent transmissions from other radio stations near the same frequency or from Soviet radio jammers trying to prevent the Germans from communicating with one another.

Once copied, the message was sent from Beaumanor to Hut 6 at Bletchley Park for processing. The important information from the intercept was entered onto a form such as the "W/T (wireless telegraphy) Red Form" shown above. The cipher groups, with corrections or alternates, were entered into the blocks on the sheet. Other intercept information — callsigns, frequency, time of intercept, and organization — was entered on the form. Once completed, this form would be forwarded to a cipher clerk, who would apply the day's key and decipher the intercepted message.

Once the deciphering of message Nr 14 was complete, the text would be entered onto the day's other German Police decrypts (Nr. 21) by Hut 3 for dissemination. If the message were to be translated that job would have been completed at Hut 3. A rough translation of the message is as follows:
To: Reichsfuehrer SS and the Chief of the Order Police.
On the Bobruisk to Mogilev road, [there was] a skirmish with partisans: 16 men from the 51st Police battalion were killed. In the town of Borki [Unlocated. There are several towns named Borki in present day Belarus — author.] where weapons and ammunition were found, and was leveled in the usual manner. The inhabitants were liquidated. From: Senior Officer SS and Police Chief Central Russia.

Western communications intelligence during the war grew from a set of small national efforts to a partnership that spanned the globe. It consisted of the major cryptologic agencies of the United States and Great Britain with supporting contingents from the Commonwealth as well as from other Allied nations. Western COMINT comprised a multistep system that set priorities for the collection, processing, and intelligence signals intelligence. Western COMINT primarily targeted Axis military, naval, and diplomatic communications. Secondary targets included the less important Axis communications and those of neutral countries. Axis and neutral communications that carried the most information about the Holocaust, German Police and international diplomatic were targeted mainly for the intelligence that these networks might contain that supported the main war effort against the Axis. Information about the Holocaust that appeared on these networks was collected as a byproduct of the main COMINT effort.

Notes

See Euna O'Halpin, "Small States and Big Secrets: Understanding SIGINT Cooperation between Unequal Powers during the Second World War." Intelligence and National Security (Vol. 17, No. 3, Autumn 2002), 1-16. For more on the relationship with France, see RG457, HCC, Box 1277, Folder 3732, "Liaison with the French on Signal Intelligence Matters," 28 November 1944; and PRO, HW 14/3, January-February 1940, "Liaison with French and Poles." For relationship with Netherlands, see PRO, HW 14/18, August 1941, "SIGINT Exchange with Dutch in the Far East." For more on the relationship with the Poles, see, among others, PRO, HW 14/8, regarding a Polish-manned intercept station in Stanmore, England.

For example, see Carl Boyd, Hitler's Secret Confidant: General Oshima Hiroshi and Magic Intelligence 1941 - 1945 (Lawrence, KS: University Press of Kansas, 1993), pages 57-74, about Axis plans for 1942 and pages 117-139 for German appreciation of the Allied intention in 1944. Also, see Hinsley, Vol. I, pages 429-493, about COMINT and other intelligence sources regarding German plans and preparations for the invasion of the Soviet Union known as Operation Barbarossa.

SRH-349, The Achievements of the Signal Security Agency in World War II (Washington DC: The Assistant Chief of Staff , G-2, 1946).

Memorandum for the Deputy Chief of Staff from Major General Clayton Bissell, Subject: Intercept Facilities. 8 September 1944. SRH-145, 200-201. Also Memorandum for Mr. McCloy from Colonel Carter Clarke, no subject 16 March 1944, SRH-145, 158-A.

For more on the phenomenon of women in these agencies, see Jennifer Wilcox, Sharing the Burden: Women in Cryptology during World War II (Fort George G. Meade, MD: Center for Cryptologic History, 1998), SRH-152, "Historical Review of OP-20-G," 1945, 3; Alvarez, 115-119.

The Enigma and Purple cipher machines are well known from the literature of World War II. Less famous, but important as sources of intelligence, were some other Axis cipher machines. Tunny was the cover name applied to the Lorenz Company's on-line enciphered teleprinter known to the Germans as Schluesselzusatz 40 or SZ-40. GC&CS first broke it in late 1941.

The Signal Intelligence Service underwent many title changes during the war. From 1929 to 1942, it was the Signal Intelligence Service. In June 1942 it was briefly renamed the Signal Intelligence Service Division. One month later it was again renamed the Signal Security Division (SSD). In 1943 the SSD became the Signal Security Service. In late summer 1943, the SSS became the Signal Security Agency (SSA). It remained the SSA until 15 September 1945 when the SSA was renamed the Army Security Agency (ASA).

The SIS would achieve its first cryptanalytic breakthrough against the main Japanese army code in April 1943. In January 1944, Australian troops captured the entire cryptographic library of a Japanese Army division that clinched the mastery of the Imperial Army's codes and ciphers. See Edward Drea, MacArthur's Ultra, 61-92, for details of the year-long struggle.

That the German military traffic was placed in Group B was a further indication that the two countries were arriving at a division of effort dictated by geography and expertise. Throughout 1942, SIS had been working on an ability to exploit Enigma, but lacked sufficient intercept, expertise, and technical information. The British refused to allow the SIS to join in the exploitation. However, by mid-1943 a compromise for exchange was worked out that formed the basis for a more formal exchange of all Axis intelligence. See Benson, 99-108.

One interesting multiforce, multinational intercept operation against clandestine Axis radio stations in North Africa occurred in North Africa in late 1944. A special effort included personnel from the SIS, the OSS and Free French forces, who operated intercept and direction-finding stations in Algiers, Tunis, and Morocco. RG 457, HCC, Box 1417, Folder 4619, "Special Report on Clandestine Radio Activity in North Africa." The OSS, though excluded from performing cryptanalysis by FDR's directive of July 1942, and prohibited from receiving COMINT by a May 1942 agreement among the Army, Navy, and FBI, still established its own intercept and D/F stations outside of the U.S.

The story of the BRUSA Agreement, which proceeded from earlier negotiations, is, itself, a tale of bureaucratic complexity. The American Army and Navy each made agreements with the British. They then had to make one between themselves. See Benson, 97-133, and Bradley Smith, 105 — 170. See also "Army-Navy Agreement Regarding Ultra." RG 457, HHC, Box 1413.

This major exception, the processing of undecrypted U-boat radio traffic by both the United States and Great Britain, began in earnest in late 1942 following the Holden Agreement of October 1942. After the installation of the American-built "bombes" at the OP-20-G Headquarters on Nebraska Avenue, N.W., in Washington, DC, the U-boat cipher text was transmitted there for decryption. The resulting translations were then transmitted to the appropriate Allied naval commands. Eventually, the bombes were turned against German Luftwaffe and Wehrmacht Enigma traffic. For more on the Holden Agreement, see Ralph Erskine, "The Holden Agreement on Naval Sigint: The First BRUSA?" Intelligence and National Security, (Volume 14, No. 2, Summer 1999), 187-197.

Initially, the U.S. Army and Navy performed this censorship mission. It was assumed by the Office of Censorship, which picked up the military censorship programs. This censorship also included all mail entering and exiting the United States. Telephone calls, whether over cable or radiotelephone, also were monitored, For a history of the Office of Censorship, see Michael Sweeney, Secrets of Victory: The Office of Censorship and the American Press and Radio in World War II (Chapel Hill, North Carolina: University of North Carolina Press, 2001). Of interest is that the eventual commander of the SIS, Colonel Preston Corderman, began his wartime service in the Office of Censorship directing and training postal censors.

For example, see Lisbon (Foreign Minister) to Washington, 22 June 1944, MC-916, in which the Washington embassy is reminded to paraphrase public text, such as speeches, so as to avoid the use of them as plaintext cribs. Also, Washington (Hopenot/Baudet) to Algiers, 13 May 1944, MC-806, in which the French Committee for National Liberation is reminded that all cables can be obtained by the "enemy" and exploited because the cables were encoded with Vichy codes. RG 457, HCC, Box 879, "Code Instructions." Also, Tokyo (Shigemetsu), 9 August 1943, warning that the Allies may purposely print news stories that diplomats would quote and thereby could endanger Japanese codes because plaintext would be known. NARA, RG 457, HCC, MND Translation #93904. Finally, Berlin (Oshima) to Tokyo, 5 March 1944, CI-1813, in which the Japanese diplomats in Germany discreetly instruct Tokyo to keep new communications routes secret from the British "telegraph office." RG 457, HCC, Box 954, folder 2863, "Japanese Message Translations Categorized as CI (Code Instructions) for Diplomats, 1943-45."

Kenneth Macksey. The Searchers: Radio Intelligence in Two World Wars (London: Cornell University Press, 2003), 108-9.

Radio frequencies are part of the electromagnetic spectrum. The most used frequency bands during World War II were very high frequency (30-300 Megahertz), high frequency (3-30 Mhz), medium frequency (300 kilohertz — 3 Mhz), and low frequency (30-300 Khz).

During the war, in 1943, the Allies developed and fielded a secure speech unit for use on HF radiotelephone circuits among the Allied commands and capitals. The system, named SIGSALY, was contained in an equipment hut that weighed 55 tons. For more on this see J.V. Boone and R.R. Peterson, The Start of the Digital Revolution: SIGSALY. Secure Digital Communications in World War II (Fort George G. Meade, MD: Center for Cryptologic History, 2000).

This control was not without a struggle. Several times early in the war, service intelligence heads tried to limit GC&CS control through bureaucratic maneuvers in the Y-Board, a committee under the JIC that managed intercept operations. See Hinsley, Volume II, 23-4 and Macksey, 129. Also PRO HW 14/30, "GC&CS Directorate, Policy Papers," "No. 6. I.S.," 1 March 1942.

"History of the Solution of Vatican Systems in SSA and GCCS, 1943-44." (Washington: September 1944) RG 457, HCC, Box 1284.

For example, it took Frank Rowlett's team in SIS from April 1939 to September 1940 to break Purple. GC&CS codebreakers took from September 1939 to July 1940 to master the Luftwaffe's Enigma, and until June 1941 to exploit the Kriegsmarine version of Engima.

For an explanation of the double playfair cipher, see "Study of German Police Traffic," NARA, RG 457, HCC, Box 202.

For a discussion of the relative difficulty of both systems, see William F. Friedman and Lambros Callimahos, Military Cryptanalytics Part I (Washington, DC: National Security Agency, 1956), 181-188, about Playfair systems. See Lambros Callimahos and William F. Friedman, Military Cryptanalytics, II (Washington, DC: National Security Agency, 1959), 431-433, for transposition systems.

For the work against the German systems, see Budiansky, 218-220 and 310-11; Alvarez, 234. Also see NARA RG 457, HCC, Box 942, Folder 2746, 11 May 1945, "GEE Problem"; Box 1317, Folder 3945, 1944, "History of Special German Diplomatic Net, Summer 1942 to Winter 1944."

Nigel West. The SIGINT Secrets: The Signals Intelligence War, 1900 to Today (New York: William Morrow, 1988), 307. See Alvarez, 176, for the Allied failure against Swedish systems. Hinsley, Vol. 2, Appendix 4, 656-668, for a summary of success against all German systems.

Hinsley, Vol. II, Appendix 5, 670-2.

Phillips, 7-11.

"Memorandum for Colonel Clarke," 3 January 1944. James L. Gilbert and John P. Finnegan, U.S. Army Signals Intelligence in World War II. A Documentary History (Washington, DC: Center of Military History, 1993), 63-4.

According to one historical review conducted by the U.S. Navy, some 300,000 German Navy messages were "read," meaning they were decrypted by the Americans or Commonwealth codebreakers. Of these, about 69,000 were German U-boat messages. About 49,600 U-boat translations were published between early 1941 to June 1945 for a rate of around 72 percent. These translations are notated "SRGN" and are available at NARA, RG 457, Entry 9019 and at the library of the National Cryptologic Museum. "Historical Review of OP-20-G, RS #77967, 8 October 1945, untitled background notes, Author's private collection.

This is a rough calculation determined by comparing the number of translations of the Japanese diplomatic collection at NARA, Entry 9011 (SRDJ), with that of the Multinational Diplomatic collection, Entry HCC, Boxes 286-516.

Rowlett, 253-5; Contrary to popular opinion, the Vatican messages were in Italian, not Latin. Switzerland had diplomatic codes for German and French texts to account for that nation's major language divisions.

Memorandum for Colonel Carter W. Clarke, Subject: "Origins, Functions, and Problems of the Special Branch, MIS." 15 April 1943, Gilbert and Finnegan, 55.

For example, see NARA, RG 457, Box 590, for "Glossary of Japanese terms," and Box 619 for "Glossary of German Army Equipments." For German Police messages, Boxes 202 and 1386 contain glossaries of abbreviations and shorthand terms used by the Police in their messages.

Non-notated and unsigned memorandum on diplomatic cryptanalysis for 1940, 31 January 1941, HW 14/11, "Government Code and Cypher School: Directorate: Second World War Policy Papers," as cited in John Ferris, "The Road to Bletchley Park: The British Experience with Signals Intelligence." Intelligence and National Security (Vol. 17, No. 1, Spring 2002), 53-84.

Many of these studies were of political and diplomatic topics. These studies were notated as Special Research Histories (SRH). Some examples include: SRH-083, "Chung-King-Yenan Controversy," and SRH-094, "French-Indo-China (Political Situation)." The SRHs can be found in NARA, RG 457 and the Library of the National Cryptologic Museum.

See SRH-035, "History of Special Branch, MIS, War Department, 1942-1944," 9 July 1979 and SRH-117, "History of Special Branch M.I.S., Jun 1944 — Sep 1945." 2 March 1981.

SRH-107, "Problems of the SSO System in World War II." 13 December 1980.

Gilbert and Finnegan, 10.

One extant European Summary, dated 11 April 1945, carried two distributions. The first one listed 11 recipients within the War Department; the second listed the President, his Chief of Staff, and the CINC U.S. Fleet, and the Deputy Director Military Intelligence, British Army Staff. SRH-005, "Use of CX/MSS Ultra by the United States War Department, 1943 — 1945," 49.

The "Magic" Diplomatic Summaries are located in RG 457, Entry 9006, Boxes 1-19. The "Magic" Far East Summaries are found in Entry 9001, Boxes 1-11.

Hinsley, Vol. I, 295-6. Churchill's demand for the COMINT grew out of dissatisfaction with the tendency of the JIC and the service intelligence directors to publish long appreciations, the "bulk of which defeats their purpose."

Churchill received GC&CS items from "C" that had not been given to the various department and ministry chiefs. They often were unaware of the material the prime minister used to criticize them. Ibid., 295-6.

Alexander S. Cochran Jr. The Magic Diplomatic Summaries: A Chronological Finding Aid (New York and London: Garland Publishing Inc., 1982). From 1942 to the end of the war in Europe, there were fewer than 12 references to Jews or the Holocaust. For example, Summary No. 397 from 28 April 1943 contains information from a German diplomatic message to Dublin concerning Aryan spouses of Jews.

Jan Karski, an alias for a Polish intelligence courier, Jan Kozielewski, visited the Warsaw ghetto and Belzec. He came to London in late 1942 with information about the Holocaust. See Laqueur, 118-120, and E. Thomas Wood and Stanislaw M. Jankowski, Jan Karski: How One Man Tried to Stop the Holocaust (New Jersey: John Wiley & Sons, 1994).

Laqueur, 94-5.

Breitman, 105, 151-3; MND Translation, Kabul (Pilger) to Berlin, 10 May 1943, SIS #81006 (RG 457, HCC, Box 363), concerning Reuters News Agency publication of information about gassing of the Jews; MND Translation, Berlin to Buenos Aires, 14 April 1943, SIS #82728(RG 457, HCC, Box 363), which urges the German embassy there to make no statement on the protests against the perceived anti-Jewish policy of Churchill. (This "anti-Jewish policy" is not further explained in the German message.); MND Translation, Berlin to Far East stations (NPD (Neue Presse Deutsche) Broadcast), 3 March 1944, SIS #112776, (RG 457, HCC, Box 399) which urges German correspondents to push stories about behind the scenes machinations of world Jewry.

Perhaps the most famous anecdote, though false, was the bombing of Coventry on 14 November 1940. Winterbotham was the first to claim that Churchill allowed Coventry to be bombed to protect the Ultra secret. (See his Ultra Secret, 94-96) However, Winterbotham got it wrong. Ultra carried no information on Coventry. For the correct story of Ultra and bombing of Coventry see Hinsley, British Intelligence in the Second World War, Vol. I., Appendix 9, 528-48, and Nigel West, A Thread of Deceit (New York: Random House, 1985), 9-17.

For the Yamamoto ambush, see SRH-288, "Radio Intelligence in WWII: Tactical Operations in the Pacific Ocean Areas, April 1943." 336-7, and Edwin Layton (along with Roger Pinneau and John Costello), And I was There, Pearl Harbor and Midway — Breaking the Secrets (New York: William Morrow and Company Inc., 1985), 474-476.

Hinsley, Vol. 2, 58-67; see also Smith, Sharing Secrets with Stalin.

Breitman, 93-4, 106.

Hinsley, Vol. II, 87-9; Smith, Sharing Secrets with Stalin, 30-33.

Breitman, 92-96; Philipps, 84-5.

It is also possible that another standing concern of the police command was the possibility that someone within the police or SS organizations might reveal information about the massacres to the Allies or neutral countries. Passing the reports by radio meant that a number of people saw the messages: radio operators, code clerks, dispatchers, etc. Sending the reports by courier limited the number of people who might see them.

On 6 December 1941, the Nobel Laureate German author, Thomas Mann, made a radio speech from Los Angeles on the CBS network in which he called attention to the massacre of 300,000 Serbs and "unspeakable deeds" against Jews and Poles. It is not clear if this speech provoked a similar reaction from the Germans. — New York Times, 7 December 1941, Vol. XCI, No. 30,633.

HW 14/54, "GC&CS Directorate, Policy Papers." 1942, October 1-10.

NARA RG 457, HCC, Box 1386, "German Police and SS Messages."

HW 14/128, "GC&CS Directorate, Policy Papers." 1945 May 16-31, Notes from 26 and 28 May. The British developed a number of categories of cover names for the various German cipher systems, both machine and manual. Here are some representative examples:
Luftwaffe: Colors (Red, Yellow)
Weather: Vegetables (Leek, Garlic)
Army: Birds (Albatross, Bullfinch)
SS: Fruit (Orange, Quince, Grapefruit)
Police (Playfair): Games (Rummy, Poker)

Breitman, 218.

For example, a Colonel Taylor, presumably Telford Taylor, was named in the distribution for CIRO/PEARL/ZIP/AT 1194/14.8.44, HW 16/70, "German Police Decrypts."